A rectangular tank measuring 85 cm by 56 cm by 37 cm was to be filled with water by two taps, H and J. Tap H which fills the tank at a rate of 5 ℓ per minute was first turned on for 4 minutes before Tap J was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap H was first turned on, what is the rate at which Tap J fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 85 x 56 x 37
= 176120 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap H
= 5000 x 6
= 30000 cm
3 Volume of water filled by Tap J
= 176120 - 30000
= 146120 cm
3 Rate in which Tap J fills the tank
= 146120 ÷ 2
= 73060 cm3/min
73060 mℓ/min
= 73.06 ℓ/min
≈ 73.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 73.1 ℓ/min